Metal beryllium hydrides and method for preparing the same

ABSTRACT

1. The method for preparing metal beryllium hydrides conforming to the formula M2(BeH4)M where M is a metal selected from the group consisting of alkali metals and alkaline earth metals and m is the valence of the metal M, which comprises mixing an organo metal beryllium compound conforming to the formula M(BeR3)M with a solution in an ether solvent of a compound conforming to the formula M(A1H4)M thereby forming a liquor containing a compound conforming to the formula A1R3 dissolved therein and a precipitated compound conforming to the formula M2(BeH4)M, being selected from the group consisting of methyl, ethyl, propyl, isopropyl, secondary butyl, tertiary butyl, isobutyl, n-pentyl, n-butyl, n-hexyl, n-octyl, Stearyl, cyclopentyl, cyclohexyl, phenyl, 1,1-diphenylhexyl, 1-phenyl-2-butenyl, 1-phenyl-1methylethyl, and 3--methyl-2-butenyl radicals.

United States Patent [72] Inventor John A. Snover Beverly Farms, Mass.

[21] Appl. No. 218,803

[22] Filed Aug. 20, 1962 [45] Patented Oct. 26, l 97 1 73] AssigneeMetal Hydrides Incorporated Beverly, Mass.

[54] METAL BERYLLIUM HYDRIDES AND METHOD Wiberg et al., 2. Naturfarsch,63, P. 171 (1951) abstracted in Chem. Abstracts, Vol. 46 (195 2),Abstracts No. 38916, copy available in POSL.

Nuclear Science Abstracts, Vol. 7 No. 3352 (1953) P. 410, copy availablein F081. QC 770 n 96.

Primary Examiner-Carl D. Quarforth Assistant Examiner-Franklin M. GittesAttorney-J. Harold Boss CLAIM: 1. The method for preparing metalberyllium hydrides conforming to the formula M (BeH where M is a metalselected from the group consisting of alkali metals and alkaline earthmetals and m is the valence of the metal M, which comprises mixing anorgano metal beryllium compound conforming to the formula M(BeR with asolution in an ether solvent of a compound conforming to the formulaM(A1H,). thereby forming a liquor containing a compound conforming tothe formula AIR dissolved therein and a precipitated compound conformingto the formula M Bel-1,) being selected from the group consisting ofmethyl, ethyl, propyl, isopropyl, secondary butyl, tertiary butyl,isobutyl, npentyl, n-butyl, n-hexyl, n-octyl, Stearyl, cyclopentyl,cyclohexyl, phenyl, l,l-diphenylhexyl, l-phenyl-2butenyl, 1-phenyl-l-methylethyl, and 3--methyl-2-butenyl radicals.

METAL BERYLLIUM HYDRIDES AND METHOD FOR PREPARING THE SAME M,(Bel-LBmwhere M is selected from alkali metals and alkaline earth metals, and mis the valence of the metal M. These compounds are useful as componentsof high-energy fuels.

The copending application of John A. Snover and Richard D. Donovan, Ser.No. 214,445, filed July 26, 1962, describes a method for preparingorganolithium beryllium compounds having the formula LiBeR, where R is ahydrocarbon radical which forms compounds conforming to the formula RLiwhich are soluble in liquid hydrocarbons, such as hexane. This methodcomprises forming a slurry of a beryllium halide such as the chloride,bromide or iodide, in a hexane solution of the compound RLi in which thecompound RLi and beryllium halide are present in the molar ratio ofabout 3 moles of the compound RLi for each mole of beryllium halide.Diethyl ether is slowly added to the slurry thereby forming a solutionof the compound LlBeR, in a mixture of hexane and diethyl ethercontaining precipitated lithium halide. The reaction is illustrated bythe equation:

3RLi +BOClrfiLilelh+2LiCl l When the precipitated lithium halide isfiltered off and the filtrate concentrated under vacuum at roomtemperature to remove the solvents, a nonvolatile liquid is obtainedconforming to the formula LiBeR v l have discovered that when a solutionof lithium aluminum hydride in diethyl ether, preferably of about 5molar concentration, is added slowly to the compound LiBeR at roomtemperature, a white precipitate of lithium beryllium hydride is formedin a solution of an aluminum compound having the formula MR The reactionis illustrated by the equation:

LiBeR,+LiAlH,'- -Li,BeH +AIR (2) The precipitated lithium berylliumhydride may be removed by filtration, washed with hexane, and driedunder vacuum at 60 C.

The diethyl ether may be replaced by other ethers, such as dipropylether, propyl methyl ether, dibutyl ether, tetrahydrofuran,tetrahydropyran, and the dimethyl ethers of ethylene and diethyleneglycol.

I have further discovered that the compounds LiBeR and LiAlH, in thereaction illustrated by equation (2) above may be replaced with othercompounds having the formulas M(BeR,),. and M(All-l,),,,, respectively,where M is an alkali metal or alkaline earth metal, such as sodium,lithium, potassium, calcium, magnesium, barium, strontium, etc., and mis the valence of the metal M.

The compounds having the formula M(BeR,),, used in the practice of theinvention may be prepared by replacing the compound RLi in the reactionillustrated by the equation (1) above by other compounds having theformula R,,,M. The compounds having the formula R,,,M may be prepared byreacting the metal M with organobromides having the formula RBr in aliquid hydrocarbon, such as hexane.

The radicals represented by R above are hydrocarbon radicals which formcompounds conforming to the formula R,,,M which are soluble in liquidhydrocarbons and which form compounds M(BeR,),. which are soluble in theether used in the practice of the invention. As illustrative of suchradicals I may mention methyl, ethyl, propyl, isopropyl, secondarybutyl, tertiary butyl, isobutyl, n-pentyl, n-butyl, n-hexyl, n-octyl,stearyl, cyclopentyl, cyclohexyl, phenyl, 1,1-diphenylhexyl, 1-phenyl-Z-butenyl, l-phenyl-l-methylethyl, and 3-methyl-2- butenylradicals.

In place of the metal aluminum hydrides having the formula M (A114,),other hydrides may be used such as metal hydrides having the formulaMl-l,,,, dissolved in aluminum alkyls having the formula AIR metalaluminum alkoxy hydrides having the formula M(AIH,OR,, where x is anumber from 1 to 3; aluminum hydride; alkyl aluminum hydrides having theformula AIR,H,,,, where y is either I or 2; and boron hydridesconforming to one of the formulas M(BH,),,, B,i-l,, or R,N:BH,.

Other methods for preparing the compounds having the formula M(BeR areknown to those skilled in the art. Thus, the organometal compound havingthe formula R,,.M may be reacted in an ether medium with anorganoberyllium compound having the formula mBeR,.

The invention is illustrated further by the following specific examples.

EXAMPLE 1 To 38.4 grams of n-butyl lithium in 360 ml. of hexane wasadded 16 grams of 99.5 percent beryllium chloride. The slurry wasstirred rapidly and cooled as 200 ml. of dry diethyl ether was addedover a period of 1 hour. This solution was filtered under a dry nitrogenatmosphere. The filtrate was concentrated under vacuum at roomtemperature. To this solution of 37.6 grams of lithium beryllium n-butylwas added dropwise over 1.5 hours a total of 7.6 grams of lithiumaluminum hydride in the form of a 5.1 molar solution in diethyl ether.Heat was evolved as a fine, white solid formed. The mixture was stirredovernight at room temperature and then filtered under dry nitrogen. Theproduct was washed with hexane and dried in vacuum at 60 C. for severalhours. The product weighed 2.98 grams and analyzed by weight percent:14.46 percent hydride, 33.1 percent beryllium, 53.8 percent lithium,0.11 percent aluminum and 2.15 percent carbon. The purity was about 96percent and the chemical yield was 54 percent.

The product obtained was found to give an X-ray diffraction patternwhich did not agree with the known d-spacings of lithium hydride,lithium aluminum hydride, lithium or beryllium metal. Beryllium hydride,which is thought to be polymeric in nature, was found to be amorphous byX-ray analysis. Therefore, it can be concluded from the X-ray analysisthat the lithium beryllium hydride produced by this example is notmerely a mixture of lithium hydride and beryllium hydride. Also, thedensity of this material was measured to be 0.722 grams/cc., which isgreater than that of beryllium hydride. Infrared spectra, both as a mulland as a KB, pellet, showed two broad bands of absorbance; one from 5.0to 8.5 micron with a maximum at 6.5 micron, the other band from 8.5 to15 micron with a small maximum at 12.2 micron.

EXAMPLE 2 The same procedure and reactants were used as in example 1except that the n-butyl lithium was replaced with an equivalent solutionof isobutyl lithium prepared by reaction of lithium metal and isobutylbromide in hexane. The product obtained was of comparable purity andyield.

EXAMPLE 3 The same procedure and reactants were used as in example 1except that the n-butyl lithium was replaced with an equivalent amountof phenyl lithium. The product obtained was of comparable purity andyield.

EXAMPLE 4 A solution of sodium beryllium tris-n-butyl, prepared bymixing a solution of bis-n-butyl beryllium with an equivalent amount ofn-butyl sodium, was reacted with a solution of sodium aluminum hydridein tetrahydrofuran. After stirring overnight, the precipitated solidswere removed by filtration, washed and dried in vacuum. A good yield ofsodium beryllium hydride, Na Bel-h, was obtained.

EXAMPLE 5 An ether solution of magnesium beryllium ethyl,Mg[Be(C,c5),},, prepared by mixing bis-ethyl beryllium with bis-ethylmagnesium in a 2 to l mole ratio, was treated with a tetrahydrofuransolution of magnesium aluminum hydride. The solids which formed werestirred for 24 hours, filtered off, washed with hexane and dried invacuum. Analysis of this product gave a mole ratio of magnesium toberyllium to hydrogen of 0.95 to 2.00 to 7.93, and only trace amounts ofaluminum were found in the product.

I claim:

1. The method for preparing metal beryllium hydrides conforming to theformula M (Bel-l where M is a metal selected from the group consistingof alkali metals and alkaline earth metals and m is the valence of themetal M, which comprises mixing an organometal beryllium compoundconforming to the formula M(BeR with a solution in an ether solvent of acompound conforming to the formula M(AlH thereby forming a liquorcontaining a compound conforming to the formula AIR, dissolved thereinand a precipitated compound conforming to the formula M (Bel-l R beingselected from the group consisting of methyl, ethyl, propyl, isopropyl,secondary butyl, tertiary butyl, isobutyl, n-pentyl, n-butyl, n-hexyl,n-octyl, stearyl, cyclopentyl, cyclohexyl, phenyl, l,l-diphenylhexyl,l-pheny-Z-butenyl, l-phenyl-lmethylethyl, and 3-methyl-2-butenylradicals.

2. The method as claimed by claim 1 wherein the hydrocarbon radical isan alkyl radical.

3. The method as claimed by claim 1 wherein the hydrocarbon radical is abutyl radical.

4. The method as claimed by claim 1 wherein the hydrocarbon radical isn-butyl.

S. The method as claimed by claim 1 wherein the metal M is lithium.

6. The method as claimed by claim 1 wherein the metal M is sodium.

7. The method as claimed by claim 2 wherein the metal M is lithium.

8. The method as claimed by claim 2 wherein the metal M is sodium.

9. The method as claimed by claim 3 wherein the metal M is lithium.

10. The method as claimed by claim 3 wherein the metal M is sodium.

11. The method as claimed by claim 4 wherein the metal M is lithium.

12. The method as claimed by claim 4 wherein the metal M is sodium.

2. The method as claimed by claim 1 wherein the hydrocarbon radical isan alkyl radical.
 3. The method as claimed by claim 1 wherein thehydrocarbon radical is a butyl radical.
 4. The method as claimed byclaim 1 wherein the hydrocarbon radical is n-butyl.
 5. The method asclaimed by claim 1 wherein the metal M is lithium.
 6. The method asclaimed by claim 1 wherein the metal M is sodium.
 7. The method asclaimed by claim 2 wherein the metal M is lithium.
 8. The method asclaimed by claim 2 wherein the metal M is sodium.
 9. The method asclaimed by claim 3 wherein the metal M is lithium.
 10. The method asclaimed by claim 3 wherein the metal M is sodium.
 11. The method asclaimed by claim 4 wherein the metal M is lithium.
 12. The method asclaimed by claim 4 wherein the metal M is sodium.